Module 4. Design aspects of dairy plant

Lesson 20


20.1 Introduction

Service pipe line layout for different services required in the dairy plant like steam, well water, chilled water, hot water, fresh water, refrigeration, air etc. is prepared for minimizing material requirement, estimating cost of installation, to facilitate selection of different fittings, and to smoothen the operation. Service pipeline layout is prepared considering safety aspects of the plant and personnel working. It also helps in deciding the material requirement, mountings and accessories required in each pipelines. There are different colour codes used for different piping systems. The steam pipe is painted with yellow colour, chilled water pipe line is painted with blue colour, well water pipeline is painted with green colour and pipelines carrying hot fluid is painted with red colour. The pipe lines carrying hot and cold fluids are insulated with suitable insulating material.

20.2 Colour Coding for Identification of Pipe-Lines

When a number of pipe lines are running in dairy factory, it becomes necessary to know what material is being piped through particular pipe. To avoid any sort of accident, it is important to identify the pipe lines. The American Society of Mechanical Engineers has suggested colour code for identification of all piping arrangement and systems.


In a milk plant, green colour for safe material, yellow for dangerous material and red for fire control equipment are used. However, an organization can used shades of these colours for further identification of more pipe lines. For instance, cold water light gren, hot water dark green, chilled light blue etc. A factory using colour code for identification of piping must display at the entrance or at a suitable place a colour identification of pipes running in the plant. This can be done by cutting small length of pipes say 4 inches and painting them; write the material being piped through against the colour painted pipe ends. These may be mounted on a board and hanged on wall so that this can be noticed by all.

20.3 Milk Piping

The layout of interconnecting milk piping system should be decided keeping in view the method of cleaning. There are two methods which are commonly adopted for cleaning milk piping. These are: (1)manual cleaning method and (2) cleaning-in-place (C.I.P.) method.

If manual cleaning method is adopted, it must be clear that the pipes have to be dismantled frequently for cleaning operations and for this purpose, it is essential that approach to pipe lines is made very easy, i.e., piping system is easily accessible. For this piping supports from ground (floor) is preferred for supporting overhead pipe lines which are 7 to 8 ft above the ground level. Piping supports should be placed at a distance of about 3 meters or about 10 ft. All pipes carrying milk are of stainless steel as they are easy to clean. Sanitary piping is recommended for dairy industry.

For cleaning-in-place method, approach to pipe line is less important as piping will be dismantled relatively infrequently. Layout of piping in C.I.P. system has to be planned carefully because the purpose is not only conveying or carrying milk but also cleaning. Contamination has to be avoided in all cases. In large installations, it will be necessary to arrange for part of the pipe system to be cleaned while another part is conveying milk, and precautions and safeguards must be incorporated to prevent accidental contamination of milk by cleaning solutions or detergents. A milk piping must be so arranged to minimize loss of product at the end of process run to ensure that all cleaning solutions are removed from plant before use. For C.I.P. cleaning of pipe lines, milk piping may be supported from ceiling. In this metal suspension rods are fixed to ceiling. This gives a clear floor area with no obstruction and operations are carried out smoothly.

Typical layouts for service pipe lines are shown in the Fig. 20.1 (a), 20.1 (b), 20.2, 20.3, 20.4, 20.5, 20.6, and 20.7.


Fig. 20.1 (a) Milk piping


Fig. 20.1 (b) Milk piping


Fig. 20.2 Typical sanitary pipe supports


Fig. 20.3 Isometric view of steam pipe line


Fig. 20.4 Isometric view of chilled water pipe line in dairy


Fig. 20.5 Isometric view of well water pipe line in dairy


Fig. 20.6 Isometric view of soft water pipe line in dairy


Fig. 20.7 Isometric view of fresh water pipe line in dairy

Last modified: Thursday, 4 October 2012, 8:59 AM